Let’s make the mundane interesting! Welcome to a detailed history of LED lights, including:
- What: LED aka light emitting diode
- The Who: Nick Holonyak
- The when: 1962
- The how: by accident
- And then where: at General Electric in America.
The caveat is that Mr. Nick Holonyak is the pioneer of the first visible LED. After this breakthrough, he became a Professor Emeritus. This is a big deal in higher education. The theory of electroluminescence and invisible LED lights was around well before 1962. Other notable mentions who made significant strides in the field of LEDs are:
- H. J. Round
- Oleg Losev
- James R. Biard
Before we get tangled up, let me break it into bite-sized chunks for you.
Back to the Basics and the Principle of Electroluminescence
The foundation of the LEDs we see daily is based on the principle of electroluminescence (EL). Electroluminescence is the creation of light from an electric current traveling through materials like semiconductors without generating heat. There are two types of EL:
- Low field EL
- High field EL
LEDs are a typical example of low-field EL. Luminescence occurs when electric current flows. When there is no electric current, there is no light. I’m talking science afterward, but I’ll keep it brief, so our eyes don’t glaze over.
What’s a Semiconductor?
A semiconductor is neither a conductor nor an insulator but has both properties under certain conditions.
- A conductor is something that conducts electricity, usually metallic.
- An insulator does not conduct electricity like rubber.
A diode, like an LED, is a semiconductor composed of several crystals, and you can control the flow of electric current in it.
The Science Behind How an LED Works
An LED is an example of a p-n junction diode emitting light when the correct voltage is applied. The electrons combine with electron holes to release photons. In a p-n junction diode, you have a p-type and n-type semiconductor. A boundary develops between them when these two semiconductors fuse. It is in this boundary that the electrical charge is stored.
What Is a Photon? Let a Little Light Shine Down on Me
A photon is a particle of light. The term photon was first used in 1926 by a chemist, Gilbert Lewis, and an optical physicist, Frithiof Wolfers. Photo means light in Greek.
Delving Into the Aptly Named P-Type and N-Type Materials
It’s complicated, but a p-type material usually has silicon or germanium (not the flower geranium). These elements are doped with a trivalent atom such as boron or indium. In LEDs, gallium is the preferred choice from group III. Silicon or germanium are IVs. Boron or indium are IIIs.
This means someone at the party doesn’t have a dance partner, leaving a hole. So, in a P-type material, you have three covalent bonds and a single electron hole. And P stands for positivity because the holes have a positive charge.
FYI – doping refers to varying the number of electrons and holes in a semiconductor. You are not drugging your lights.
N-type material is made up of IVs and Vs. N stands for negativity because this semiconductor has a negative charge. Our group V elements are phosphorus, arsenic, or antimony, and these pairings result in an extra electron. Again, we have silicon or germanium, but now we have four pairs and an extra electron.
But What About LEDs Specifically?
Silicon is not great for light emission. LEDs are made from one of the following compound combinations from groups III and V of the periodic table.
- Indium gallium nitride (InGaN) – blue, green, and ultraviolet LEDs
- Aluminum gallium indium phosphide (AlGaInP) – yellow, orange, and red LEDs
- Aluminum gallium arsenide (AlGaAs) – red and infrared LEDs
- Gallium phosphide (GaP) – yellow and green LEDs
The common denominator here is your group III element, Gallium (Ga). The original LED was made from gallium arsenide phosphide (GaAsP) and emitted a red light. Today, we get LEDs in different colors depending on the compound combination.
A Brief History of Light
I think we’ve covered enough science for now. Let’s get back to the topic at hand. What is the history of light? We’ve all heard of Thomas Edison, credited as the inventor of the incandescent light bulb. But, as much as you and I would like it to be neat, the history of the modern world has many half-truths.
Yes, Thomas Edison was involved with the invention and design of the light bulb. He patented the incandescent light bulb for commercial use. (That man liked paperwork because he patented things prolifically.)
But, a team of researchers and other inventors worldwide contributed to the lights we are lucky enough to have around us daily. A British gentleman called Sir Humphrey Davy produced the first true artificial electric light. He did this by using a battery, some wires, and some carbon. Sadly, it didn’t last very long, but it helped lay the groundwork.
Another Brit, Joseph Swan, worked on and patented a type of light bulb before Edison did on his side of the pond. There was a lawsuit, but eventually, Swan and Edison joined forces to form Edison-Swan United, a global manufacturer of light bulbs.
Other notable mentions include William Sawyer and Albon Man.
What Came After the Incandescent Light Bulb?
I like to call this the untangling of the Christmas lights because the history of lights and lamps is not straightforward. Our starting point is the incandescent light bulb. After that came the Geissler tube, invented in Germany by a glassblower, Heinrich Geissler, and physicist Julius Plücker.
After the Geissler tube came Peter Cooper Hewitt’s blue-green lamp, unpopular because of its color. And after that, the Europeans experimented with neon tubes coated in phosphors. The Americans didn’t want to be left out. They came up with the fluorescent lamp, used by the American navy because it was much more energy efficient than an incandescent light bulb.
If you want to know what a fluorescent lamp is, think of those usually hideous, long white tubes that emit glaring bright white light. These lights show up in every pore and wrinkle in factory-style buildings. It’s practical but not pretty. When I was a child, we had one in our kitchen.
After the fluorescent light came the compact fluorescent light (CFL), which was initially pricey. However, now these lights are value-for-money and long-lasting. Imagine the white tube in small spirals. You might even have one or two in your home.
You also get a halogen lamp, an incandescent lamp filled with one of the halogen gases. These were invented in 1955 and are common in the residential and commercial light market.
After these lightbulbs came the LED lights. They were invented between the halogen lamp and the CFL but were not widespread until the early 2000s for residential applications.
The Rise of the LED Light
We’ve covered what came before LED lights, so let’s return to the esteemed Nick Holynoak. The first visible LED light was red. And because it was energy efficient and durable, it was used for circuit boards and small electrical equipment. Think of your 90s electronic equipment. So many of them will contain an LED light. Your television remote, for example, flashes an infrared light, but it’s an LED.
Throughout the 1960s, there was LED experimentation, and different chemical substrates produced varying colors of red and orange.
Monsanto was the first company to mass produce LED lights. In 1972, Dr. George Craford at Monsanto used a red and a green diode to create a light-yellow LED light. Craford’s LED was much brighter than the one by Prof. Nick Holynoak.
More colors became available as the years went on. In 1994, Isamu Akasaki, Hiroshi Amano, and Shuji Nakamura completed the LED rainbow by creating/inventing/innovating ultra-bright blue LEDs and winning a Nobel prize for their success.
And finally, we came full circle, and scientists created the white LED but coating a blue LED with fluorescent phosphor. Thank you, Prof. Dr. Jürgen Schneider, for your contribution to lighting up our world.
Why LEDs Are Winning at Lighting up Our Homes
LEDs are a vital technological advancement. We are so not advanced that we do not need to rely on fossil fuels. This means that lighting that is energy efficient is essential. Their manufacture is also more environmentally friendly than some of the lights that use mercury.
Longevity is important too. LEDs last a good long while when compared to other lights and lamps. They come in a dazzling array of colors, and they are multipurpose. LEDs are used in many industries worldwide, including aeronautical, automotive, and medical.
LED lights are the all-rounder you need on your team in your business and home.